MHA能够在10~30秒内实现自动故障检测和故障转移，适用于对高可用性，数据完整性要求较高的场合。要做到无缝切换，还需要依赖于VIP漂移。VIP漂移比较常用的方式为使用keepalived或者使用脚本直接实现。脚本方式无须安装及复杂配置，相对简单。本文描述了基于脚本实现VIP切换。
1、当前主机环境及MHA配置?
[root@vdbsrv1 ~]# more /etc/hosts
127.0.0.1? ? localhost.localdomain localhost
192.168.1.6? vdbsrv1? #master
192.168.1.7? vdbsrv2? #slave1
192.168.1.8? vdbsrv3? #slave2
192.168.1.12 vdbsrv4? #manager
###os环境
[root@vdbsrv4 ~]# more /etc/issue
CentOS release 5.9 (Final)
Kernel \r on an \m
?
###mysql环境
[root@vdbsrv4 ~]# mysql -e "show variables like 'version'"
+---------------+------------+
| Variable_name | Value? ? ? |
+---------------+------------+
| version? ? ? | 5.6.22-log |
+---------------+------------+
[root@vdbsrv4 ~]# masterha_manager --version
masterha_manager version 0.56.
###MHA配置信息
[root@vdbsrv4 ~]$ more /etc/masterha/app1.cnf
[server default]
manager_workdir=/var/log/masterha/app1
manager_log=/var/log/masterha/app1/manager.log
user=mha
password=xxx
ssh_user=root
repl_user=repl?
repl_password=repl?
ping_interval=1
shutdown_script=""
master_ip_online_change_script=""
report_script=""
master_ip_failover_script=/tmp/master_ip_failover
?
[server1]
hostname=vdbsrv1
master_binlog_dir=/data/mysqldata
[server2]
hostname=vdbsrv2
master_binlog_dir=/data/mysqldata
[server3]
hostname=vdbsrv3
master_binlog_dir=/data/mysqldata/
#candidate_master=1
2、测试VIP切换
###测试VIP(192.168.1.13)是否被启用
[root@vdbsrv4 ~]# ping 192.168.1.13
PING 192.168.1.13 (192.168.1.13) 56(84) bytes of data.
From 192.168.1.12 icmp_seq=10 Destination Host Unreachable
###为主机vdbsrv1添加VIP
[root@vdbsrv4 ~]# ssh vdbsrv1 "/sbin/ifconfig eth0:0 192.168.1.13 netmask 255.255.255.0 up"
###校验VIP是否成功启用
[root@vdbsrv4 ~]# ping 192.168.1.13
PING 192.168.1.13 (192.168.1.13) 56(84) bytes of data.
64 bytes from 192.168.1.13: icmp_seq=1 ttl=64 time=1.82 ms
###开启MHA
[root@vdbsrv4 ~]# masterha_manager --conf=/etc/masterha/app1.cnf &
###模拟主库宕机
[root@vdbsrv4 ~]# ssh vdbsrv1 "killall -r mysqld"
###查看管理节点日志，可以看到VIP已经漂移
[root@vdbsrv4 ~]# grep VIP /var/log/masterha/app1/manager.log
Disabling the VIP on old master: vdbsrv1
Enabling the VIP - 192.168.1.13/24 on the new master - vdbsrv2
###验证VIP是否位于节点vdbsrv2
[root@vdbsrv4 ~]# ssh vdbsrv2 "ifconfig |grep 1.13 -B1"
eth0:0? ? Link encap:Ethernet? HWaddr 00:0C:29:5F:B2:EB?
? ? ? ? ? inet addr:192.168.1.13? Bcast:192.168.1.255? Mask:255.255.255.0
######查看管理节点MHA切换日志
[root@vdbsrv4 ~]# tail /var/log/masterha/app1/manager.log
Invalidated master IP address on vdbsrv1(192.168.1.6:3306)
The latest slave vdbsrv2(192.168.1.7:3306) has all relay logs for recovery.
Selected vdbsrv2(192.168.1.7:3306) as a new master.
vdbsrv2(192.168.1.7:3306): OK: Applying all logs succeeded.
vdbsrv2(192.168.1.7:3306): OK: Activated master IP address.
vdbsrv3(192.168.1.8:3306): This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
vdbsrv3(192.168.1.8:3306): OK: Applying all logs succeeded. Slave started, replicating from vdbsrv2(192.168.1.7:3306)
vdbsrv2(192.168.1.7:3306): Resetting slave info succeeded.
Master failover to vdbsrv2(192.168.1.7:3306) completed successfully.
3、VIP切换perl脚本
[root@vdbsrv4 app1]# more /tmp/master_ip_failover
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
my (
? ? $command,? ? ? ? ? $ssh_user,? ? ? ? $orig_master_host, $orig_master_ip,
? ? $orig_master